Internal liquid conductivity measuring meter for living plants - uses square wave oscillator, discriminator and AC millivolt-meter

摘要

The instrument gives a visual indication of the liquid conductivity, i.e the reciprocal of the specific resistance, of the liquid in various parts of growing plants. The output of an asymmetrical oscillator (6) is fed to two thin metal needles (4) which protrude from an insulated block (5) and are inserted into the plant. The change in the oscillator signal caused by the current flowing through the plant tissue is detected by a discriminator (7) and displayed on a linear or logarithmic scaled millivoltmeter (8).